The last of five articles in which The Post's art critic chooses a single detail from a single painting to dwell on.

The Phillips's old-fashioned music room is the perfect place to end a week of old-fashioned art looking. Tucked into a corner of that room is El Greco's "Repentant Saint Peter." Tucked into a corner of that painting is one of the most striking details in this entire museum: a little figure of a rushing woman so outlandish, you'd think it was painted in Paris circa 1910, not three centuries earlier in Toledo.

That's why Duncan Phillips added El Greco's work to his collection: In 1922, he saw this master of the Spanish baroque as "the prophet of modern painting," an early champion of stylization and abstraction and radical expression, almost a Picasso wannabe.

But are we right to read a 17th-century painting -- this collection's second-oldest work -- through 20th-century eyes? It seems pretty clear that ideas like "stylization" or "expressivity" depend on the context they're used in. El Greco's paintings may not always have read as "weird" or "angstful." After all, there was no photography or academic realism to compare them to. They could as easily have read as elegant and graceful and charming. Or, more likely, as simply "good," without a lot of adjectives or comparisons attached.

If we conceive of El Greco's little figure as taking baby steps toward modern style, we're tempted to ignore the important content she conveys. The steps she's really taking are toward Saint Peter, who stands in the foreground of this painting bewailing the three times he denied Jesus as his master. Our little figure is his fellow disciple Mary Magdalene, the ex-prostitute who has just discovered her resurrected savior's empty tomb -- she'd gone there to anoint the body and is still carrying her trademark ointment jar -- and is now rushing off to give her friends the news. (You can just see the torchlit tomb far off behind her.)

What we see as forward-looking "style" in this painting may be less about a new look than the traditional content it is made to carry. Part of that content involves space and depth. Because of the strange games El Greco plays with scale, he's got to find a way to make clear that the Magdalene is a full-size figure in the distance, not a puppet by Peter's elbow. The painter does that partly by making all the subjects close to us much sharper and more natural than subjects farther back -- from the sharp-focus, highly rendered ivy in front, to Saint Peter himself, to Mary Magdalene, to the almost indecipherable tomb in the far distance. This range of treatments gives us a clue to how un-modern this picture really is: Instead of coming up with a consistently new way of viewing the world -- a unique and personal optic to look at it through -- El Greco is building a picture around the different jobs he's got for its components. He wants the Magdalene and Peter side by side on the surface of the picture, so resurrection and repentance can be aligned in people's minds. But he also wants to register the space that sits between his figures as his picture tells its story.

He also needs his rushing woman, however small, to register as a sex worker in her working clothes. (In El Greco's day, making a picture of this saint was often the barest excuse for showing a beautiful girl.) By painting the Magdalene gorgeously, stylishly, El Greco could appropriately boost her sex appeal. His brushwork is a good stand-in for a brothel's flowing silks.

It's also a decent substitute for divine light. El Greco's white paint is where he goes most wild. It's all over the Magdalene, almost defining her form. It sticks to Peter's keys (the keys to papal Rome, and thus this Catholic saint's crucial equipment), to his face and beard and especially his eyes as they fill with sanctified tears. That white paint almost obliterates the angel just behind Mary Magdalene, who brought her news of Christ's rising.

El Greco's angel is flashy and unreal, in properly modern style. But its flash may be about religious realism.